macros: Simplify Response derive attribute parsing

crates/ruma-macros/src/api/attribute.rs

@@ -12,7 +12,6 @@ mod kw {
     syn::custom_keyword!(query);
     syn::custom_keyword!(query_map);
     syn::custom_keyword!(header);
-    syn::custom_keyword!(manual_body_serde);
 }
 
 pub enum RequestMeta {
@@ -76,20 +75,3 @@ impl Parse for ResponseMeta {
         }
     }
 }
-
-#[allow(clippy::large_enum_variant)]
-pub enum DeriveResponseMeta {
-    ManualBodySerde,
-}
-
-impl Parse for DeriveResponseMeta {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        let lookahead = input.lookahead1();
-        if lookahead.peek(kw::manual_body_serde) {
-            let _: kw::manual_body_serde = input.parse()?;
-            Ok(Self::ManualBodySerde)
-        } else {
-            Err(lookahead.error())
-        }
-    }
-}

crates/ruma-macros/src/api/response.rs

@@ -4,17 +4,20 @@ use proc_macro2::TokenStream;
 use quote::{quote, ToTokens};
 use syn::{
     parse::{Parse, ParseStream},
-    punctuated::Punctuated,
     visit::Visit,
-    DeriveInput, Field, Generics, Ident, Lifetime, Token, Type,
+    DeriveInput, Field, Generics, Ident, Lifetime, Type,
 };
 
-use super::attribute::{DeriveResponseMeta, ResponseMeta};
+use super::attribute::ResponseMeta;
 use crate::util::import_ruma_common;
 
 mod incoming;
 mod outgoing;
 
+mod kw {
+    syn::custom_keyword!(manual_body_serde);
+}
+
 pub fn expand_derive_response(input: DeriveInput) -> syn::Result<TokenStream> {
     let fields = match input.data {
         syn::Data::Struct(s) => s.fields,
@@ -28,13 +31,9 @@ pub fn expand_derive_response(input: DeriveInput) -> syn::Result<TokenStream> {
             continue;
         }
 
-        let metas =
-            attr.parse_args_with(Punctuated::<DeriveResponseMeta, Token![,]>::parse_terminated)?;
-        for meta in metas {
-            match meta {
-                DeriveResponseMeta::ManualBodySerde => manual_body_serde = true,
-            }
-        }
+        let _ = attr.parse_args::<kw::manual_body_serde>()?;
+
+        manual_body_serde = true;
     }
 
     let response =